When creating a recipe say 13C (oatmeal stout) kepping everything else constant is there a difference and or preference from using all dark extract (dme or liquid) as opposed to using a combination of dark and light other then it would change the final color? I am trying to add more character via the grain bill. I have used all dark in the past (with good results) but want to combine light with some dark getting most of my color through the addition of the grains. Again any feedback is much appreciated.

When all grainers make a stout, they use the equivalent of light LME/ DME as the base and add specialty grains to impart the color and flavor. NB has a Dry Irish Stout that uses a pound of Roasted Barley and two pounds of Flaked Barley to add color and mouth feel. These, combined with specific hops and yeast, produce one awesome stout. Their recipes are posted and are worth taking a look. I have yet to find one unsatisfactory.

Northern Brewer makes some pretty awesome kits and they also publish their recipes on their site. I have 2 brew buddies that purchase their kits on a regular basis....and of course I have the chance to sample their finished product. They make a great kit.

There's nothing wrong with combining any liquid extracts as long as you have a good knowledge of their fermentabilty and what each type contributes to the final product.

To learn a lot more on extract brewing...I would have to recommend the book, Brewing Classic Styles authored by Jamil Zainasheff and John Palmer. This book is geared for the extract brewer and contains a lot of good information about extract brewing, and includes recipies to go with each BJCP style.